PROJECT SUMMARY/ABSTRACT This application seeks to develop a non-invasive and practical optical sensor technology to monitor and quantify oxidative health. Oxidative stress (OS) is a biochemical imbalance in which production of reactive oxygen species exceeds the system?s antioxidant capacity. Failure to repair or contain cumulative oxidative damage is likely responsible for the pathogenesis of many acute and chronic illnesses, including cardiovascular and kidney disease, inflammatory responses, neurodegenerative disorders, and carcinogenesis. A noninvasive, inexpensive, robust sensor capable of evaluating and monitoring systemic oxidative stress would be a tool of great value to public health officials, clinicians, and individual consumers since many environmental conditions and xenobiotics (e.g., urban air pollution, heavy metal contamination, endocrine disrupting compounds, pesticides, and industrial chemicals) trigger oxidative stress. Because there is no universal biomarker for OS and there are many potential target molecules, it?s critical to develop a system that is capable of detecting many chemical components and creating a chemical fingerprint that reflects alterations in key pathways associated with environmental stressors. iSense, LLC has developed a novel sensor array that can detect a vast library of volatile compounds across multiple chemical moieties at ppb-level concentrations. The technology is rapid, inexpensive, and capable of distinguishing between single analytes and complex mixtures. Our breath sensor has been used to detect the biosignature of lung cancer patients and differentiate between different types of lung cancer in humans. Phase I of this project will test, improve, and optimize this breath analysis technology towards the detection and identification of key biomarkers of oxidative stress. Successful completion of this work will establish the fundamental chemistry necessary to develop a device to measure and understand markers of environmental exposure.